HOUSTON -- The Astros didn't even wait until they arrived in Houston to solve one of their two open roster spots for Opening Day.Utility infielder Matt Duffy earned the nod, manager A.J. Hinch said Thursday, meaning the Astros will carry 13 position players and 12 pitchers for the first several series. Hinch said he informed Duffy -- who kept the knowledge quiet even in pregame interviews before an exhibition game against Milwaukee -- on the plane ride from Florida on Wednesday night.Tyler White beat Duffy out for the starting first-base job, but by all accounts, Duffy's spring was solid. While his average dipped, Duffy still posted a .725 OPS with three homers and seven RBIs in 47 spring at-bats."He balances out our bench pretty well." Hinch said. "As a right-handed hitter who can play first and third -- we've introduced left field to him, too -- he's versatile enough, has power, puts up a good at-bat, and we have some left-handedness at third base and the outfield."We just felt like he was a good guy to start the season with the left-handed relievers we're going to face in the first few series. His efficient swing off the bench makes sense."It's a seminal moment for Duffy, though it won't be his MLB debut. The former 20th-round pick was a September callup last season and recorded three hits and three RBIs in just eight at-bats.It's clear this will be a bench role for the third baseman by trade, with pinch-hit duty, extra-innings work and platoon situations likely to dictate his playing time. Evan Gattis' eventual return in April could also make Duffy's time in the Majors short-lived, barring further injuries.For now, it also means the Astros are going with Duffy's bat over a couple of bullpen arms competing for a final long relief spot. Wandy Rodriguez, Michael Feliz and James Hoyt are the contenders for the gig, Hinch said."We're going to meet here today and tomorrow and go through it one more time," Hinch emphasized Thursday. "You pound your head against the wall because there's not a bad choice between the three of them."